In a way we are all Guardians. Some guard only themselves, others restrict their sphere of influence to just family or friends, and still others extend their sphere of protection even further. All is fine, but you might find that depending on your thoughts about how far your influence can reach, it actually will reach!
And sure, we are not all part of Marvel's Universe, but we do pack an awesome bunch of skill, talent, power and perseverance! So go out and do for mankind whatever you think needs doing, whether it is helping feed the homeless in your immediate neighborhood, or contributing your awesome programming powers to an initiative like Open Assistant, in order to buiild a true AGI that will help mankind immensely.
In the end the scope at which you operate is not important, but the quality of your contribution is. So don't worry if you can't impact today's society like Elon Musk, but be content that whatever you are doing for those around you is enough!